Field of the Invention
The invention relates generally to a cutting tooth for use with a stump cutting apparatus; and, more specifically, a cutter bit or tip for a stump cutting tooth.
Description of Related Art
Stump cutters or stump cutting machines are generally known in the art and are used to cut or grind stumps. A typical stump cutter includes a plurality of cutting tools mounted to a rotatable cutting wheel or drum. Placing the wheel or drum against a stump and rotating it causes the cutting tools, and more particularly individual cutting teeth, to engage and cut away the stump. Tool holders, sometimes referred to as pockets, secure the cutting teeth to the cutting wheel.
One type of stump cutting tool assembly includes a cutting tooth and tool holder/pocket assembly. The cutting tooth may include a cutting tip or bit made of a solid material such as tungsten carbide and a generally cylindrical shank that extends through an aperture in a mounting block or pocket. As known, changing each cutting tooth can be expensive. Increasing cutting bit life correspondingly decreases downtime during cutting tool changeover thereby increasing the overall desirability of a cutting tooth.
Furthermore, cutting efficiency has a direct impact on the size of the power source required to operate a stump cutting tool. Reduced efficiency means that a larger, more inefficient engine or motor must be used, thereby increasing purchase cost of the machine, transportation costs to-and-from job sites, and operating costs. Because a stump grinding machine presents an atypical circumstance when compared with most cutting and grinding operations, the typical and obvious steps taken in these other industries to improve cutting efficiency is not generally applicable. Such atypical circumstances include the hard/dense wood with diverse grain patterns encountered in a tree stump, the necessary penetration of earth when grinding portions of the stump below the ground level, and the inevitable encountering of rocks and other buried objects. As such, stump grinding teeth must be extraordinarily robust and tough. They must hold an edge for an extended working life without breakage. Another atypical circumstance relevant to tree stump grinding pertains to the unique motion of a cutting wheel in normal operation. In particular, stump grinding is most often executed by lowering a high-speed spinning cutting wheel into a tree stump, and then laterally swinging the cutter wheel from side-to-side while progressively advancing the blade ever deeper. This unique motion (rotation plus side-to-side) requires many different surfaces of the cutting teeth to ferociously cut into the wood. However, adverse machining vibrations, known generally as chatter, are common when aggressively moving the cutting tool relative to the tree stump. Such chatter produces harsh vibrations that can prematurely damage teeth and bearings, can bend or warp the body of a cutting wheel, and can unduly fatigue the operator. Chatter is therefore preferably avoided or at least minimized. And still yet another atypical aspect of stump grinding is the need, or at least the desire, to produce relatively consistent shredded wood pulp during the cutting operation. Large curls of wood fiber are generally considered not acceptable, as are fine wood dust at the other extreme.
There is therefore a need in the art for improvements in cutting efficiency that accommodate the numerous atypical circumstances of tree stump cutting/grinding, that produce consistent moderately sized wood shavings, and that avoid or at least minimize the occurrence of chatter.